1. Field of the Invention
The present invention relates to vehicle transmissions, and particularly to transmissions having a large number of speed variations, e.g., for work vehicles such as agricultural tractors.
2. Description of the Related Art
U.S. Pat. No. 4,345,490 (Madson) depicts a transmission having a wide range of speeds, and theoretically 27 gear ratios. However, it has been found in practice that because of the extreme closeness of several of the resultant gear ratios, the structure taught in the '490 patent does not provide 27 gear ratios which are useful in practice.
It is not feasible simply to add another brake or clutch to the end of the structure shown in the '490 patent because this results in a number of clutch and brake discs and separators moving in opposite directions in many gear settings. Such a structure would create a high amount of turbulence in the oil in the system, and would be prone to breakdown.